SMTP Relay
The process of forwarding email from one SMTP server to another. When you send an email, your mail client submits it to an outgoing SMTP server (port 587), which relays it through one or more intermediate servers until it reaches the recipient's mail server. Each hop returns SMTP reply codes indicating success (250) or failure (550 mailbox not found, 421 try again).
相关协议
相关场景
550 Mailbox Not Found — Email Bouncing
SMTP
421 Service Unavailable — SMTP Connection Refused
SMTP
550 Relay Access Denied — Cannot Send Through SMTP Server
SMTP
554 Transaction Failed — Blacklisted IP
SMTP
535 Authentication Failed — App Password Required
SMTP
452 Insufficient Storage — Mailbox Full
SMTP
503 Bad Sequence of Commands — AUTH Before STARTTLS
SMTP
421 Service Unavailable — STARTTLS Required
SMTP